The harp seal, Pagophilus groenlandicus (Erxleben, 1777). III. The underwater audiogram

1972 ◽  
Vol 50 (5) ◽  
pp. 565-569 ◽  
Author(s):  
J. M. Terhune ◽  
K. Ronald
Keyword(s):  
Ambient Noise ◽  
Free Field ◽  
Phoca Vitulina ◽  
Harp Seal ◽  
Pagophilus Groenlandicus ◽  
Increased Sensitivity

A free-field underwater audiogram from 0.76 to 100 kHz was obtained for Pagophilus groenlandicus. Areas of increased sensitivity occurred at 2 and 22.9 kHz. The lowest threshold was −32.9 db/μbar at 15.0 kHz. Above 64 kHz the threshold increases at a rate of 40 db/octave. The audiogram was similar to that of the Phoca vitulina. The effects of ambient noise on the audiogram are discussed.

The harp seal, Pagophilus groenlandicus (Erxleben 1777). XXIII. Spectral sensitivity

1972 ◽  
Vol 50 (9) ◽  
pp. 1197-1206 ◽  
Author(s):  
D. M. Lavigne ◽  
K. Ronald
Keyword(s):  
Spectral Sensitivity ◽  
Dark Adaptation ◽  
Relative Sensitivity ◽  
Visual Sensitivity ◽  
Harp Seal ◽  
Scotopic Sensitivity ◽  
Underwater Environment ◽  
Pagophilus Groenlandicus ◽  
Increased Sensitivity ◽  
Purkinje Shift

Behavioral determinations of harp seal spectral sensitivity, under light- and dark-adapted conditions, indicated the presence of a Purkinje shift. Maximum photopic sensitivity occurred near 550 nm. Scotopic sensitivity peaked in the region of 500–525 nm. A large increase in relative sensitivity, approaching 8 log units at 525 nm, accompanied dark adaptation. This confirms anatomical suggestions that the harp seal possesses excellent visual sensitivity. Increased sensitivity to green wavelengths may indicate adaptation to a particular underwater environment.

The harp seal, Pagophilus groenlandicus (Erxleben, 1777). X. The air audiogram

1971 ◽  
Vol 49 (3) ◽  
pp. 385-390 ◽  
Author(s):  
J. M. Terhune ◽  
K. Ronald
Keyword(s):  
Middle Ear ◽  
Acoustic Impedance ◽  
Pure Tone ◽  
Free Field ◽  
External Auditory Meatus ◽  
Harp Seal ◽  
Impedance Mismatch ◽  
Pagophilus Groenlandicus

A free-field air audiogram from 1 to 32 kHz was obtained for a Pagophilus groenlandicus trained to respond to pure tone signals. The lowest threshold was at 4 kHz at a level of 29 db//0.0002 dynes/cm2. The air audiogram was generally flat. The critical ratios at 2 and 4 kHz were 10%. The lumen of the external auditory meatus is probably acoustically blocked. The outer and (or) middle ear structures and their acoustic impedance mismatch with the air are believed responsible for the comparatively irregular and slightly insensitive hearing of the seal in air.

Changes in fatty acid composition of plasma of the harp seal Pagophilus groenlandicus during the post-weaning fast

1981 ◽  
Vol 70 (4) ◽  
pp. 795-798
Author(s):  
Bruce A. Bailey ◽  
R.G.H. Downer ◽  
D.M. Lavigne ◽  
G. Drolet ◽  
G.A.J. Worthy
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Acid Composition ◽  
Harp Seal ◽  
Pagophilus Groenlandicus

scholarly journals Estimation of harp seal (Pagophilus groenlandicus) pup production in the North Atlantic completed: results from surveys in the Greenland Sea in 2002

2006 ◽  
Vol 63 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Tore Haug ◽  
Garry B. Stenson ◽  
Peter J. Corkeron ◽  
Kjell T. Nilssen
Keyword(s):  
North Atlantic ◽  
Barents Sea ◽  
Temporal Distribution ◽  
Harp Seal ◽  
Greenland Sea ◽  
The North ◽  
Pagophilus Groenlandicus ◽  
Pack Ice ◽  
Photographic Survey ◽  
Strip Transect

Abstract From 14 March to 6 April 2002 aerial surveys were carried out in the Greenland Sea pack ice (referred to as the “West Ice”), to assess the pup production of the Greenland Sea population of harp seals, Pagophilus groenlandicus. One fixed-wing twin-engined aircraft was used for reconnaissance flights and photographic strip transect surveys of the whelping patches once they had been located and identified. A helicopter assisted in the reconnaissance flights, and was used subsequently to fly visual strip transect surveys over the whelping patches. The helicopter was also used to collect data for estimating the distribution of births over time. Three harp seal breeding patches (A, B, and C) were located and surveyed either visually or photographically. Results from the staging flights suggest that the majority of harp seal females in the Greenland Sea whelped between 16 and 21 March. The calculated temporal distribution of births were used to correct the estimates obtained for Patch B. No correction was considered necessary for Patch A. No staging was performed in Patch C; the estimate obtained for this patch may, therefore, be slightly negatively biased. The total estimate of pup production, including the visual survey of Patch A, both visual and photographic surveys of Patch B, and photographic survey of Patch C, was 98 500 (s.e. = 16 800), giving a coefficient of variation of 17.9% for the survey. Adding the obtained Greenland Sea pup production estimate to recent estimates obtained using similar methods in the Northwest Atlantic (in 1999) and in the Barents Sea/White Sea (in 2002), it appears that the entire North Atlantic harp seal pup production, as determined at the turn of the century, is at least 1.4 million animals per year.

Calling depth and time and frequency attributes of harp (Pagophilus groenlandicus) and Weddell (Leptonychotes weddellii) seal underwater vocalizations

2005 ◽  
Vol 83 (11) ◽  
pp. 1438-1452 ◽  
Author(s):  
Hilary B Moors ◽  
John M Terhune
Keyword(s):  
Light Condition ◽  
Weddell Seal ◽  
Harp Seal ◽  
Vertical Array ◽  
Vocal Cords ◽  
Leptonychotes Weddellii ◽  
Call Duration ◽  
Weddell Seals ◽  
Pagophilus Groenlandicus ◽  
Breeding Seasons

Harp seal (Pagophilus groenlandicus (Erxleben, 1777)) daytime calling depth during the breeding season and Weddell seal (Leptonychotes weddellii (Lesson, 1826)) daytime and nighttime calling depth during the winter and breeding seasons were investigated using a small vertical array with hydrophones placed at depths of 10 and 60 m. Rough calling depth estimates (<35 m, ~35 m, >35 m) and more accurate point depth estimates (±5–10 m in most cases) were obtained. Significantly more calls were produced at depths ≤35 m for both species. The point depth estimates indicated that the calls occurred most frequently at depths >10 m; 60% of harp seal calls and 71% of Weddell seal calls occurred at depths between 10 and 35 m. The seals called predominately within areas of the water column where light would likely penetrate, but still avoided sea-ice interference to some extent. The vocalizations did not change over depth with respect to call type, the number of elements within a call, or total call duration, or with respect to season and light condition for Weddell seals. Frequency (kHz) of calls also did not change with depth, suggesting that harp and Weddell seals control the pitch of their vocalizations with the vocal cords of the larynx.

Preliminary Underwater Observations of the Breeding Behavior of the Harp Seal (Pagophilus groenlandicus)

1978 ◽  
Vol 59 (1) ◽  
pp. 181-185 ◽  
Author(s):  
B. R. Merdsoy ◽  
W. R. Curtsinger ◽  
D. Renouf
Keyword(s):  
Harp Seal ◽  
Breeding Behavior ◽  
Pagophilus Groenlandicus

Functional Hematology of the Harp Seal Pagophilus groenlandicus

1971 ◽  
Vol 44 (3) ◽  
pp. 162-170 ◽  
Author(s):  
J. R. Geraci
Keyword(s):  
Harp Seal ◽  
Pagophilus Groenlandicus

Influence of vessel noises on underwater vocal activity of harp seals

1979 ◽  
Vol 57 (6) ◽  
pp. 1337-1338 ◽  
Author(s):  
J. M. Terhune ◽  
R. E. A. Stewart ◽  
K. Ronald
Keyword(s):  
Marked Decrease ◽  
Harp Seal ◽  
Pagophilus Groenlandicus ◽  
Vocal Activity

Recordings of harp seal (Pagophilus groenlandicus) underwater vocalizations were obtained on whelping patches in the Gulf of St. Lawrence, Canada. The seals vocalized throughout the day and night. A marked decrease in seal vocalizations occurred following the arrival of a vessel. The relatively loud motor noises of the vessel completely masked the seal calls (within a 2-km or more radius) except during the night when the vessel's motors were shut down. The decreased seal vocalizations may reflect a change in the seal's behaviour and (or) movement of some seals away from the area of the vessel.

scholarly journals A Neurological Comparative Study of the Harp Seal (Pagophilus groenlandicus) and Harbor Porpoise (Phocoena phocoena) Brain

2010 ◽  
Vol 293 (12) ◽  
pp. 2129-2135 ◽  
Author(s):  
Solveig Walløe ◽  
Nina Eriksen ◽  
Torben Dabelsteen ◽  
Bente Pakkenberg
Keyword(s):  
Comparative Study ◽  
Harp Seal ◽  
Phocoena Phocoena ◽  
Harbor Porpoise ◽  
Pagophilus Groenlandicus

Population and density of the bipolar ganglion cells in the cochlea of the harp seal (Pagophilus groenlandicus Erxleben, 1777)

1976 ◽  
Vol 54 (11) ◽  
pp. 1918-1926 ◽  
Author(s):  
F. Ramprashad
Keyword(s):  
Hair Cells ◽  
Ganglion Cells ◽  
Spiral Ganglion ◽  
Harp Seal ◽  
Nerve Cell Body ◽  
Continuous Ring ◽  
Average Value ◽  
Pagophilus Groenlandicus ◽  
Sensory Hair Cells ◽  
Two Peaks

The population and density of the bipolar ganglion cells were determined from serial horizontal sections and graphic reconstructions of the cochleas of five captive harp seals. The [Formula: see text]-turn spiral ganglion forms a continuous ring throughout its course except at the extreme basal end where it is narrowest. The nerve cell body is 25 μm long (16.1–38.8 μm) and 16 μm wide (10–24 μm). The average number of ganglion cells present was 57 185 (46 389 – 70 952), with a corrected total number of 52 000 ganglion cells. Two peaks are present in the density curve of the ganglion cells. The first was at 1–1.5 mm and the second at 20 mm, where 2620 cells/mm2 and 2250 cells/mm2 respectively are present.The ratio of total ganglion cells to total sensory hair cells was about 3:1. This ratio was not uniform throughout the length of the cochlea; it was 6:1 at 2–3 mm from the basal end and declined gradually to 3:1 at the apical end. The average total of ganglion cells in the harp seal exceeded the average value in humans, but did not exceed the values found in dolphins.

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